‘False negative’ has tracers on the run

Thousands of Victorians have been ordered to undertake urgent COVID-19 tests after a hotel quarantine worker returned a false negative test and then later tested positive.

The line outside the Sunbury Respiratory Clinic in Melbourne last Thursday for Covid-19 testing. Picture: Getty Images

Thousands more Victorians have been ordered to undertake urgent COVID-19 tests and isolate after a rare false negative test returned by a hotel quarantine worker, who later tested positive, sent contact tracers scrambling to investigate new sites of potential public exposure dating back almost a week.

A woman in her 50s and a three-year-old child who attended a private function in ­Coburg on February 6 along with the worker from the Holiday Inn have tested positive for coronavirus, it emerged on Sunday.

The mother of the child has been tested but has returned conflicting results, including a weak positive, that are undergoing further investigation. Her workplace contacts at Alfred Health have been tested as a precaution.

The function venue on Sydney Road in Melbourne’s northern suburbs was confirmed as an exposure site only late on Friday.

As a result, several extra potential public exposures have emerged dating back to February 8, including a Woolworths supermarket and Ferguson Plarre bakehouse in Broadmeadows and two swim and recreation centres in Pascoe Vale.

The Queen Victoria market has been declared an exposure site after an infected individual visited early on February 11.

Victoria’s testing commander Jeroen Weimar said the hotel worker returned a positive test on February 10 but the Coburg social gathering was not identified in initial conversations with contact tracers. He said the female worker, who was being tested regularly, had also been tested on February 7, with the result coming up as negative. “We reviewed that negative result (on Saturday) … that sample has been reprocessed, it’s now returned a weak positive result,” he said.

“Our lead assumption … is that she was possibly a positive case on the 6th [and] 7th, having contracted it on the 3rd and 4th.”

Of the 38 people who attended the function, all have been isolating since February 12 and have undergone testing. “Apart from those I’ve mentioned, they’ve all tested negative so we’re confident we’ve got good ring around that event,” Mr Weimar said.

The Holiday Inn cluster has so far infected 16 people across nine households and of the 129 direct family, workplace or close social contacts identified, 127 have tested negative. All 12 colleagues of the infected Brunetti’s worker have tested negative, as have a significant number of customers.

Health Minister Martin Foley said it was too soon to ascertain whether the snap five-day lockdown was having the desired effect and declined to say whether the stage four restrictions, which have closed most businesses, caused events to be cancelled and sent more than one million schoolchildren home to learn, would be extended: “It’s too early to say whether we’ve been successful but the signs show Victorians are doing the right thing … and our test, trace and isolate system is staying ahead of this.”

Chief Health Officer Brett Sutton defended the government’s commentary around the “hyper-infectious” variant of COVID-19 that is at the centre of the latest outbreak, after experts pointed to Public Health England figures suggesting an individual infected with the UK strain would pass the virus on to 14.7 per cent of their close contacts, compared with 11 per cent transmission for the original Wuhan strain.

“Whether it’s 40 per cent or 70 per cent [more infectious] … we don’t want this variant … to be in the community and transmitting,” Professor Sutton said.

Epidemiologist Catherine Bennett said false negative results were rare and likely due to fluctuating viral loads in early stages of infection. She said the latest cases would require a strong public health response, given the time infected individuals had been able to circulate in the community.